[net-next 13/13] igb: Consolidate creation of Tx context descriptors into a single function

Jeff Kirsher
2011-09-17T08:04:53Z

From: Alexander Duyck <alexander.h.duyck@intel.com>

This patch is meant to simplify the transmit path by reducing the overhead
for creating a transmit context descriptor. The current implementation is
split with igb_tso and igb_tx_csum doing two separate implementations on
how to setup the tx_buffer_info structure and the tx_desc. By combining
them it is possible to reduce code and simplify things since now only one
function will create context descriptors.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
drivers/net/ethernet/intel/igb/igb_main.c | 233 +++++++++++++----------------
1 files changed, 106 insertions(+), 127 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index afa0ca9..563224a 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -45,6 +45,9 @@
#include <linux/pci-aspm.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/sctp.h>
#include <linux/if_ether.h>
#include <linux/aer.h>
#include <linux/prefetch.h>
@@ -3960,16 +3963,39 @@ set_itr_now:
#define IGB_TX_FLAGS_VLAN_MASK 0xffff0000
#define IGB_TX_FLAGS_VLAN_SHIFT 16

+void igb_tx_ctxtdesc(struct igb_ring *tx_ring, u32 vlan_macip_lens,
+ u32 type_tucmd, u32 mss_l4len_idx)
+{
+ struct e1000_adv_tx_context_desc *context_desc;
+ u16 i = tx_ring->next_to_use;
+
+ context_desc = IGB_TX_CTXTDESC(tx_ring, i);
+
+ i++;
+ tx_ring->next_to_use = (i < tx_ring->count) ? i : 0;
+
+ /* set bits to identify this as an advanced context descriptor */
+ type_tucmd |= E1000_TXD_CMD_DEXT | E1000_ADVTXD_DTYP_CTXT;
+
+ /* For 82575, context index must be unique per ring. */
+ if (tx_ring->flags & IGB_RING_FLAG_TX_CTX_IDX)
+ mss_l4len_idx |= tx_ring->reg_idx << 4;
+
+ context_desc->vlan_macip_lens = cpu_to_le32(vlan_macip_lens);
+ context_desc->seqnum_seed = 0;
+ context_desc->type_tucmd_mlhl = cpu_to_le32(type_tucmd);
+ context_desc->mss_l4len_idx = cpu_to_le32(mss_l4len_idx);
+}
+
static inline int igb_tso(struct igb_ring *tx_ring,
struct sk_buff *skb, u32 tx_flags, u8 *hdr_len)
{
- struct e1000_adv_tx_context_desc *context_desc;
- unsigned int i;
int err;
- struct igb_tx_buffer *buffer_info;
- u32 info = 0, tu_cmd = 0;
- u32 mss_l4len_idx;
- u8 l4len;
+ u32 vlan_macip_lens, type_tucmd;
+ u32 mss_l4len_idx, l4len;
+
+ if (!skb_is_gso(skb))
+ return 0;

if (skb_header_cloned(skb)) {
err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
@@ -3977,8 +4003,8 @@ static inline int igb_tso(struct igb_ring *tx_ring,
return err;
}

- l4len = tcp_hdrlen(skb);
- *hdr_len += l4len;
+ /* ADV DTYP TUCMD MKRLOC/ISCSIHEDLEN */
+ type_tucmd = E1000_ADVTXD_TUCMD_L4T_TCP;

if (skb->protocol == htons(ETH_P_IP)) {
struct iphdr *iph = ip_hdr(skb);
@@ -3988,6 +4014,7 @@ static inline int igb_tso(struct igb_ring *tx_ring,
iph->daddr, 0,
IPPROTO_TCP,
0);
+ type_tucmd |= E1000_ADVTXD_TUCMD_IPV4;
} else if (skb_is_gso_v6(skb)) {
ipv6_hdr(skb)->payload_len = 0;
tcp_hdr(skb)->check = ~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
@@ -3995,131 +4022,85 @@ static inline int igb_tso(struct igb_ring *tx_ring,
0, IPPROTO_TCP, 0);
}

- i = tx_ring->next_to_use;
-
- buffer_info = &tx_ring->tx_buffer_info[i];
- context_desc = IGB_TX_CTXTDESC(tx_ring, i);
- /* VLAN MACLEN IPLEN */
- if (tx_flags & IGB_TX_FLAGS_VLAN)
- info |= (tx_flags & IGB_TX_FLAGS_VLAN_MASK);
- info |= (skb_network_offset(skb) << E1000_ADVTXD_MACLEN_SHIFT);
- *hdr_len += skb_network_offset(skb);
- info |= skb_network_header_len(skb);
- *hdr_len += skb_network_header_len(skb);
- context_desc->vlan_macip_lens = cpu_to_le32(info);
-
- /* ADV DTYP TUCMD MKRLOC/ISCSIHEDLEN */
- tu_cmd |= (E1000_TXD_CMD_DEXT | E1000_ADVTXD_DTYP_CTXT);
-
- if (skb->protocol == htons(ETH_P_IP))
- tu_cmd |= E1000_ADVTXD_TUCMD_IPV4;
- tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
-
- context_desc->type_tucmd_mlhl = cpu_to_le32(tu_cmd);
+ l4len = tcp_hdrlen(skb);
+ *hdr_len = skb_transport_offset(skb) + l4len;

/* MSS L4LEN IDX */
- mss_l4len_idx = (skb_shinfo(skb)->gso_size << E1000_ADVTXD_MSS_SHIFT);
- mss_l4len_idx |= (l4len << E1000_ADVTXD_L4LEN_SHIFT);
+ mss_l4len_idx = l4len << E1000_ADVTXD_L4LEN_SHIFT;
+ mss_l4len_idx |= skb_shinfo(skb)->gso_size << E1000_ADVTXD_MSS_SHIFT;

- /* For 82575, context index must be unique per ring. */
- if (tx_ring->flags & IGB_RING_FLAG_TX_CTX_IDX)
- mss_l4len_idx |= tx_ring->reg_idx << 4;
-
- context_desc->mss_l4len_idx = cpu_to_le32(mss_l4len_idx);
- context_desc->seqnum_seed = 0;
-
- buffer_info->time_stamp = jiffies;
- buffer_info->next_to_watch = i;
- buffer_info->dma = 0;
- i++;
- if (i == tx_ring->count)
- i = 0;
+ /* VLAN MACLEN IPLEN */
+ vlan_macip_lens = skb_network_header_len(skb);
+ vlan_macip_lens |= skb_network_offset(skb) << E1000_ADVTXD_MACLEN_SHIFT;
+ vlan_macip_lens |= tx_flags & IGB_TX_FLAGS_VLAN_MASK;

- tx_ring->next_to_use = i;
+ igb_tx_ctxtdesc(tx_ring, vlan_macip_lens, type_tucmd, mss_l4len_idx);

- return true;
+ return 1;
}

static inline bool igb_tx_csum(struct igb_ring *tx_ring,
struct sk_buff *skb, u32 tx_flags)
{
- struct e1000_adv_tx_context_desc *context_desc;
- struct device *dev = tx_ring->dev;
- struct igb_tx_buffer *buffer_info;
- u32 info = 0, tu_cmd = 0;
- unsigned int i;
-
- if ((skb->ip_summed == CHECKSUM_PARTIAL) ||
- (tx_flags & IGB_TX_FLAGS_VLAN)) {
- i = tx_ring->next_to_use;
- buffer_info = &tx_ring->tx_buffer_info[i];
- context_desc = IGB_TX_CTXTDESC(tx_ring, i);
-
- if (tx_flags & IGB_TX_FLAGS_VLAN)
- info |= (tx_flags & IGB_TX_FLAGS_VLAN_MASK);
-
- info |= (skb_network_offset(skb) << E1000_ADVTXD_MACLEN_SHIFT);
- if (skb->ip_summed == CHECKSUM_PARTIAL)
- info |= skb_network_header_len(skb);
-
- context_desc->vlan_macip_lens = cpu_to_le32(info);
-
- tu_cmd |= (E1000_TXD_CMD_DEXT | E1000_ADVTXD_DTYP_CTXT);
-
- if (skb->ip_summed == CHECKSUM_PARTIAL) {
- __be16 protocol;
+ u32 vlan_macip_lens = 0;
+ u32 mss_l4len_idx = 0;
+ u32 type_tucmd = 0;

- if (skb->protocol == cpu_to_be16(ETH_P_8021Q)) {
- const struct vlan_ethhdr *vhdr =
- (const struct vlan_ethhdr*)skb->data;
-
- protocol = vhdr->h_vlan_encapsulated_proto;
- } else {
- protocol = skb->protocol;
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ if (!(tx_flags & IGB_TX_FLAGS_VLAN))
+ return false;
+ } else {
+ u8 l4_hdr = 0;
+ switch (skb->protocol) {
+ case __constant_htons(ETH_P_IP):
+ vlan_macip_lens |= skb_network_header_len(skb);
+ type_tucmd |= E1000_ADVTXD_TUCMD_IPV4;
+ l4_hdr = ip_hdr(skb)->protocol;
+ break;
+ case __constant_htons(ETH_P_IPV6):
+ vlan_macip_lens |= skb_network_header_len(skb);
+ l4_hdr = ipv6_hdr(skb)->nexthdr;
+ break;
+ default:
+ if (unlikely(net_ratelimit())) {
+ dev_warn(tx_ring->dev,
+ "partial checksum but proto=%x!\n",
+ skb->protocol);
}
+ break;
+ }

- switch (protocol) {
- case cpu_to_be16(ETH_P_IP):
- tu_cmd |= E1000_ADVTXD_TUCMD_IPV4;
- if (ip_hdr(skb)->protocol == IPPROTO_TCP)
- tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
- else if (ip_hdr(skb)->protocol == IPPROTO_SCTP)
- tu_cmd |= E1000_ADVTXD_TUCMD_L4T_SCTP;
- break;
- case cpu_to_be16(ETH_P_IPV6):
- /* XXX what about other V6 headers?? */
- if (ipv6_hdr(skb)->nexthdr == IPPROTO_TCP)
- tu_cmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
- else if (ipv6_hdr(skb)->nexthdr == IPPROTO_SCTP)
- tu_cmd |= E1000_ADVTXD_TUCMD_L4T_SCTP;
- break;
- default:
- if (unlikely(net_ratelimit()))
- dev_warn(dev,
- "partial checksum but proto=%x!\n",
- skb->protocol);
- break;
+ switch (l4_hdr) {
+ case IPPROTO_TCP:
+ type_tucmd |= E1000_ADVTXD_TUCMD_L4T_TCP;
+ mss_l4len_idx = tcp_hdrlen(skb) <<
+ E1000_ADVTXD_L4LEN_SHIFT;
+ break;
+ case IPPROTO_SCTP:
+ type_tucmd |= E1000_ADVTXD_TUCMD_L4T_SCTP;
+ mss_l4len_idx = sizeof(struct sctphdr) <<
+ E1000_ADVTXD_L4LEN_SHIFT;
+ break;
+ case IPPROTO_UDP:
+ mss_l4len_idx = sizeof(struct udphdr) <<
+ E1000_ADVTXD_L4LEN_SHIFT;
+ break;
+ default:
+ if (unlikely(net_ratelimit())) {
+ dev_warn(tx_ring->dev,
+ "partial checksum but l4 proto=%x!\n",
+ l4_hdr);
}
+ break;
}
+ }

- context_desc->type_tucmd_mlhl = cpu_to_le32(tu_cmd);
- context_desc->seqnum_seed = 0;
- if (tx_ring->flags & IGB_RING_FLAG_TX_CTX_IDX)
- context_desc->mss_l4len_idx =
- cpu_to_le32(tx_ring->reg_idx << 4);
+ vlan_macip_lens |= skb_network_offset(skb) << E1000_ADVTXD_MACLEN_SHIFT;
+ vlan_macip_lens |= tx_flags & IGB_TX_FLAGS_VLAN_MASK;

- buffer_info->time_stamp = jiffies;
- buffer_info->next_to_watch = i;
- buffer_info->dma = 0;
+ igb_tx_ctxtdesc(tx_ring, vlan_macip_lens, type_tucmd, mss_l4len_idx);

- i++;
- if (i == tx_ring->count)
- i = 0;
- tx_ring->next_to_use = i;
-
- return true;
- }
- return false;
+ return (skb->ip_summed == CHECKSUM_PARTIAL);
}

#define IGB_MAX_TXD_PWR 16
@@ -4140,8 +4121,6 @@ static inline int igb_tx_map(struct igb_ring *tx_ring, struct sk_buff *skb,
buffer_info = &tx_ring->tx_buffer_info[i];
BUG_ON(hlen >= IGB_MAX_DATA_PER_TXD);
buffer_info->length = hlen;
- /* set time_stamp *before* dma to help avoid a possible race */
- buffer_info->time_stamp = jiffies;
buffer_info->next_to_watch = i;
buffer_info->dma = dma_map_single(dev, skb->data, hlen,
DMA_TO_DEVICE);
@@ -4160,7 +4139,6 @@ static inline int igb_tx_map(struct igb_ring *tx_ring, struct sk_buff *skb,
buffer_info = &tx_ring->tx_buffer_info[i];
BUG_ON(len >= IGB_MAX_DATA_PER_TXD);
buffer_info->length = len;
- buffer_info->time_stamp = jiffies;
buffer_info->next_to_watch = i;
buffer_info->mapped_as_page = true;
buffer_info->dma = skb_frag_dma_map(dev, frag, 0, len,
@@ -4176,6 +4154,7 @@ static inline int igb_tx_map(struct igb_ring *tx_ring, struct sk_buff *skb,
buffer_info->bytecount = ((gso_segs - 1) * hlen) + skb->len;
buffer_info->gso_segs = gso_segs;
tx_ring->tx_buffer_info[first].next_to_watch = i;
+ tx_ring->tx_buffer_info[first].time_stamp = jiffies;

return ++count;

@@ -4304,7 +4283,7 @@ static inline int igb_maybe_stop_tx(struct igb_ring *tx_ring, int size)
netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
struct igb_ring *tx_ring)
{
- int tso = 0, count;
+ int tso, count;
u32 tx_flags = 0;
u16 first;
u8 hdr_len = 0;
@@ -4333,16 +4312,12 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
tx_flags |= IGB_TX_FLAGS_IPV4;

first = tx_ring->next_to_use;
- if (skb_is_gso(skb)) {
- tso = igb_tso(tx_ring, skb, tx_flags, &hdr_len);

- if (tso < 0) {
- dev_kfree_skb_any(skb);
- return NETDEV_TX_OK;
- }
- }
+ tso = igb_tso(tx_ring, skb, tx_flags, &hdr_len);

- if (tso)
+ if (tso < 0)
+ goto out_drop;
+ else if (tso)
tx_flags |= IGB_TX_FLAGS_TSO;
else if (igb_tx_csum(tx_ring, skb, tx_flags) &&
(skb->ip_summed == CHECKSUM_PARTIAL))
@@ -4366,6 +4341,10 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
igb_maybe_stop_tx(tx_ring, MAX_SKB_FRAGS + 4);

return NETDEV_TX_OK;
+
+out_drop:
+ dev_kfree_skb_any(skb);
+ return NETDEV_TX_OK;
}

static inline struct igb_ring *igb_tx_queue_mapping(struct igb_adapter *adapter,
--
1.7.6